CVE-2026-86039 — libp2p is a JavaScript implementation of the libp2p networking stack.¶

Key facts

CVE-2026-86039 is a High (8.2) vulnerability: libp2p is a JavaScript implementation of the libp2p networking stack.. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-86039
Severity	High (8.2)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-86039/

Details¶

English | 한국어

Description¶

libp2p is a JavaScript implementation of the libp2p networking stack. From 8.0.0 until 12.0.24, @libp2p/peer-store in packages/peer-store/src/index.ts uses consumePeerRecord to verify a RecordEnvelope signature but does not require PeerRecord.peerId in the signed payload to equal the signer peer ID derived by RecordEnvelope.openAndCertify. The expectedPeer option checks only the envelope signer, and the gossipsub Peer Exchange path can provide the attacker's own peer ID as expectedPeer. An attacker can therefore sign a record with the attacker's key, place a victim peer ID and attacker-controlled multiaddrs in the payload, and have certified addresses stored for the victim. The poisoned addresses can cause address-book corruption, dial redirection or failure, routing manipulation, and reachability disruption, although the connection upgrade still verifies remote peer identity and prevents a complete identity takeover. The issue is fixed in version 12.0.24.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-86039
CVSS Score	8.2

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-86039/poc.py

Usage¶

# Run PoC against target
python3 poc.py --target <TARGET_URL>

# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>

⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.

Test Lab¶

This repository includes a Docker-based test environment with both vulnerable and patched applications.

Quick Start¶

# Clone and navigate to CVE directory
cd CVE-2026-86039

# Start both applications
docker-compose up -d

# Run tests
./run-tests.sh    # Linux/Mac
./run-tests.ps1   # Windows PowerShell

Application Endpoints¶

Application	URL	Status
Vulnerable App	http://localhost:8080	Shows vulnerability
Patched App	http://localhost:8081	Demonstrates fix

Directory Structure¶

├── README.md           # English documentation
├── README_KO.md        # Korean documentation
├── poc.py              # PoC detection script
├── docker-compose.yml  # Container orchestration
├── run-tests.sh        # Linux/Mac test runner
├── run-tests.ps1       # Windows test runner
├── vulnerable-app/     # Vulnerable version
│   ├── app.py
│   ├── Dockerfile
│   └── requirements.txt
└── patched-app/        # Fixed version
    ├── app.py
    ├── Dockerfile
    └── requirements.txt

References¶

https://github.com/libp2p/js-libp2p/commit/3bf5d395cbca1488eea6e87cd771e4613b661c30
https://github.com/libp2p/js-libp2p/pull/3570
https://github.com/libp2p/js-libp2p/releases/tag/peer-store-v12.0.24
https://github.com/libp2p/js-libp2p/security/advisories/GHSA-vrf4-mx87-p53w

Generated by PoC Generator on 2026-09-18T04:56:57.279254752

Frequently asked questions¶

What is CVE-2026-86039?¶

CVE-2026-86039 is a High (8.2) vulnerability: libp2p is a JavaScript implementation of the libp2p networking stack.. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-86039?¶

Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.

How do I block or mitigate CVE-2026-86039?¶

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

For authorized security testing and research only. See the full source and NVD record.